Signal and control system



Jan. 13, 1931. M. E. FULTZ 1,783,513

SIGNAL AND CONTROL SYSTEM Filed Jan. 28, 28 6 Sheets-Sheet. 1

33.11713, 1931. FULTZ 1,788,513

SIGNAL AND CONTROL SYSTEM Filed Jan. "28, 1928 6 Sheets-$heei 2 Z Z; I J Z ("W w w w 36/11 262 Jan. 13, 1931. FULTZ 788,513

SIGNAL AND CONTROL SYSTEM Filed Jan. 28, 1928 6 Sheets-Sheef 5 75 245,, jfl/ 2m /5 //4 V 7; m m, 59%

Jan. 13, 1931. M. E. FULTZ 1,788,513

SIGNAL AND CONTROL SYSTEM Filed Jan. 28, 1928 6 Sheets-Sheet 4 45561 '/a 4d 4m U m m 4 0? m 12% a mg 65% mam/rm? M/Lf Z. F002 Jan. 13, 1931. M. E. FULTZ 1,788,513

SIGNAL AND CONTROL SYSTEM Filed Jan. 28, 1928 e Sheets-Sheet 5 JZ/ J47 f 5 g Lw gw/ m U 0 Q 5% Arm/wry Jan. 13, 1931. J u -rz 1,788,513

SIGNAL ANIE) CONTROL SYSTEM Filed Jan. 28, 1928 6 Sheets-Sheet 6 b 0W2 60d Patented Jan. 13, 1931 arisen; su mzgor BRooKIiYN'; new YORK, AssIGN'oR, r BELL; retardant. Linens- Ton-ms, 'IivooRroRAr-nn, on NEW YORK, N. Y; A con'roRAir-ron.o'rNEwYoRx siGNAL Ann CONTROL SYSTEM Application fild J'anuary ZS, 192s. Serial No; 25 o,155.'

:This invention relates tosignal and control circnits v for electric r discharge devices and particidarly .for'ihigh power electric discharge devices of thewatercooled-type, and

5 has-for an object to providean automatic sig- .nal and control circuit therefor.

other'object'of the invention is to provide automatic means for completely deenergizing: a-systeni of electric discharge devices upon the occurrence ofan undesirable operating condition. a y

A further object of the invention isto provide switching means for the signal and control circuit of a plurality of banks of electric discharge devices so that a one or more of the banks-may be operated while the others are held inirese'rve. y

Previously, control: systems have been enoployed in which the occurrence ot pan undesirable operatin condition, such. asa-failureof the cooling water. supply, woulddisconnect the supply-of; space current from the tubes. However, it has been found that even with such systems the tubes are/likely to be in ured betore-the-cathode heating current can be manually disconnected. c

lhe specific system tobe hereindescril e5 which embodies the, variousifeatures of the invention, comprises a three-stage amplifier 0 circuit, the first stage including a-single water cooled :vacuninmtube amplifier, the Second stage including two similar tubes connected in parallel, and the third stage hincluding three banks each comprisingaqplurality.oi" 5 parallel connected water/cooled vacuum' tubes; ,The three banks otthethird stageiare so arrangedhthat under norinal conditions, two are operated in parallel while the, third is held in. reserve. In; addition to the three amplifierstages, there. is provided; a single water cooled tube which is employed in a peak voltmeter circuit; Plate current for all of the tubes'is supp-lied froni a"siX-'phaserectifier in wl'iich' there are also usedwater cooled 5 vacuuintubes. 7

For the purposes OTiE- control, the system is divided up into six units, the appar'atus co1nprisingeach unit beingmo'unted in: a iseparate wire cage. The first unitcomprises the rectifier apparatus, the -secondxunit comprises contacts controlle 7 "time controlled relayiof the rectifier "unit.

the first two amplifier stages, thefthird,

'iourthi and lifthfunits comprise respectively,

the three banks of the third amplifier stage, and thersixth unit comprisesthepeak voltmeter circuit.

Each unit is provided with a group of relay operated switches. One relay for, each unit is controlled bya switch associatedwith the door of the cage which encloses it, a:nd a secend is associated with a cooling Water circulating system. ofthe tubes ofthatiu-nit. I 1 This second. relay: will be operated if. the. rate oi dowof cooling water; falls below-a certain predetermined value. Therectifier and'anpliiier units are also eachrprovided with one relay which is operatedwhenl the temperature of the cooling Water, exceeds; a predetermined Value, and with a second; relay rwhich is open ated lby an increase, above a: predetermined value,-"inl:the plate current/suppliedto any tube of the unit. In; addition; there are,pro-' vided relays which rare" operated by the, discharge of horn gaps associated with the-grid and plate bus-bars or conductors. i c

Associated withrthecircuit is a controlsfand signal system. comprising a master control circuit and two auxiliaryrcontrolvicircuits.

The master control circuit includes the "contacts of all of the above imentioned relays and also: of inter-lockingrelays which are associated=;with= each 0f1thtl11f86yll1llt$ constituting the third amplifier stage. The inter-locking relays are sovarra'nged that plate current cc'annot be supplied to thestubes of any ofthe units of that stageu-ntib atter biasing potential has 1 been; applied, to the grids of thetubes in that unit. The control circuit is supplied with current-from the source of :grid;;biasing potential and: is arranged tooperatea no-voltage :IGlBEtSE CQll of acircuit: breaker-connected inthe holding coilcircuit of the threerphase oil switch or circuit breaker through: which power supplied through-the rectifier unit to the Hamplifier system. 7 V c g One of the auxiliary circuits includes contacts of the waterflow controlled relays of the rectifier 3 and peak voltmeter units v and by the water tempera- This auxiliary circuit controls a no-voltage release coil of the circuit breaker thr ugh which heating current is supplied to the filaments of the rectifier and peak voltmeter tubes.

The second auxiliary control circuit includes contacts of the water flow nd water temperature controlled relays of each of the amplifier units. This circuit controls a novoltage release coil of the circuit breaker through which heating current supplied to the filaments of the amplifier tubes.

The circuit of the holding coil of the three phase oil switch includes in series the circuit breaker associated with the master control circuit, contacts associated with the circuit breaker for supplying heating current to the filaments of the rectifier and voltmeter tubes, contacts associated with the circuit breaker of the amplifier filament heating circuit, contacts associated with the circuit breaker included in the grid biasing potential supply circuit, and contacts associated with a switch for grounding the plate bus-bar. The opening of any of these circuit breakers, or closing of the plate busbar grounding switch will cause the oil switch to open and thereby disconnect the power source from the rectifier circuit.

The organization principle of operation, together with the objects and features of the invention will be more readily understood by reference to the following detailed description taken in connection with the drawing in which Figs. 1 to 6 placed. side by side show onespecific embodiment thereof applied to a three stage hi 'h power amplifier system.

Referring to the drawing there is shown a three stage high power amplifier circuit. The first stage comprises a single water cooled space discharge tube 201, the second stage comprises two parallel connected water cooled space discharge tubes 202, and the third stage comprises three banks 300, 100 and 500 of parallel connected water cooled space discharge tubes. Banks 300 and 500 are identical and each comprises ten parallel connected tubes 301 and 501, re-

spectively, only four of which are shown in each bank. Bank 00 comprises fifteen parallel connected tubes 401, only two of which are shown. Banks 300, 4:00 and 500 are so arranged that any or all may be operated at one time as hereinafter described. Normally two banks are operated in parallel and the remaining one is held in reserve. A peak voltmeter 600 employing a two element water cooled space discharge tube 601 is connected to the output of the third stage.

R rectifier circuit Space current for the amplifier tubes is supplied from a six phase rectifier 100 which comprises twelve two-element water cooled space discharge tubes 101, only four of w ich are shown. These tubes are connected in the usual manner through the multi-phase transformer 102 and the oil switch or circuit breaker 105 to the high voltage three phase source 10 to constitute a six phase rectifier, two tubes are connected in parallel in each side of each phase.

The plates of the tubes are respectively connected through'the relays 107, jacks 108 and ammeter 109 to ground.

The other side of the rectifier circuit is connected through inductance coils 110 and 111 (Fig. 2) to the plate bus 12. The jacks 108 provide a means for connecting the meter 113 to measure the current supplied to the bus-bar 12, through the respective rectifiers.

Heating current is supplied to cathodes of the rectifier tubes from the alternating current generator 11 through the circuit breaker 17, conductors 11 1 and the transformers 114. The plate supply circuit for the rectifiers is provided with horn gaps 115 to prevent eXccss voltages in the line from being applied to the rectifiers.

Resistances 116 are connected in each horn gap circuit to limit the current which is supplied to the relay 117 when the respective horn gap arcs over. The contacts of the relay 117 are connected in one of the control circuits, so that current flowing through any of the horn gaps will operate the relay 117 to open the oil circuit breaker 105, as will be hereinafter described.

A switch 20 (Fig. 2) is provided for grounding the plate bus-bar 12 when the amplifier system is not in use. This switch is provided with auxiliary contacts 21 which, as will be described later, prevent the operation of the system except when the switch is in the correct position.

The amplifier tubes are supplied with cathode heating current from a three phase alternating current generator 13 (Fig. 2) through circuit breaker 18. Biasing potential is supplied to the grids of the tubes in the several amplifier stages from a 275 volt direct current generator 141 (Fi 1) through circuit breaker 19 and conductor 19a.

Filters 204, 205 and 206 are provided for eliminating ripples from the potential applied to the grids of tubes 201, 202 and to the grids of the tubes in banks 800, 4:00 and 500, respectively. The biasing potential for banks 300, 400 and 500 is supplied over the conductor 206a. A ball spark gap 207 is connected in the output of the filter 206 to prevent the application of excessive grid voltages to the tubes.

The resistance 208 limits the current which flows through the winding of the relay 209 when the gap 207 arcs over. The operation of the relay 209 opens the oil circuit breaker 105, as will be hereinafter described.

Unit 200 Cathode heating current for the tubes 201 and 202is supplied from source 13 through contacts 262 of switch230 and the transformers 210 and 211 respectively. 7 'Space current for these tubes is supplied from the bus 12 through switch 212. Retard coils 213 and" 214 are connected in the plate circuits of the tubes 201 and 202 respectively to prevent coupling between the plate circuits of the I tubes in the two amplifier stages through the plate current supply circuit. i

When switch 212 is closed in the righthandposition the plates of the tubes 201 and 202 are grounded and the auxiliary contact 215is closed to operate the relay 252, to be hereinafter referred to,'and complete the main control circuit. This arrangement insures that,when the first two amplifier stages are not in use, the plates of the tubes are grounded before the rest of the circuit can be operated, as will be later described.

A horn gap 220 is provided to prevent the application of excessive voltages to the plates of the tubes 201 and 202. The resistance 221 limits the current which flows through the winding of the relay 222 when the gap 220 arcs over. Operation of the relay 222 causes 7 the oil switch 105to be opened in the same Way as the operation function.

A resistance 223 is connected in shunt to the cathode of the tube 201, and a relay 224 is connected in the plate current path of the tubebetween the mid-point of the resistance 223v and ground.

Similar, relays 225 are connected in. the plate current circuits of the tubes 202, betweenthe inidepoints of resistances 226 and ground. Thecontacts of the relays 224 and 225 are connected in the circuit including relay. 250 having a contact. in the main control of relay 117 efi'ects this circuit, so t-hat,if thespace currentsupplied toany of the tubes 201 andv 202 exceeds a predetermined value, the power supplysource will be disconnected from the system by the operation of oil switch 105.- i

The output of the amplifier tube 201 is coupled to the input of the tubes 202 by means otresistance 216. Similarly, the networks 218, 219 and 403 (Fig. 4) providemeans for coupling the output circuit of the tubes 20.2

tothe amplifier banks 300, 100 and.500.

Units 300, and 500 The input circuits of the banks 300, 400 and 500 are connected inparallel by .meansof the deltaimpedance network-403. Switches. 304, 404:; and- 504-. A are provided for connecting the grid'circuits 01E- therespective banks 300, 400 and 500 to juhe \terminals oi the. networkAOS, By n ieans of the network and. switches 304i, 404 and anyone-.01 more ot-s-thegbanks may l: e..connecte,d1 for. operation, or any two grounded contact, whereby the grid circuit 7 will be connected directly tothe ground.

Associated with the s ltches are auxiliary acts 306, 4:06 l 506, respectively, conu ed in circuit with the relays 356, 456 and each having a contact in the main control circuit, will be described later, the relays 356, and 556 operate, when any bank is connected for operation, to prevent the application of en rgizingpotential to the plates of the tubes in that bank until after the grid biasing potential has been applied to the grids of the tubes.

Blatc current torthc banks 300, and 500 is supplied from the bus-bar 15 which connected to the mainbus-bar 12 through he. high frequency choke coil 16 which is provided to prevent coupling between the plate circuits'oi these banks and Switches e07, L07 and 507 are provided for connecting the plates of the tubes'ot the respective banks to the bus-bar 15. The switches are equippedwith ground and auxiliarycontacts 308 and 309, 4-08 and 409, and 5508 and 50.9, respectively, The contacts 308, 08 and 508 providemeans for grounding the plates of the tubes in the respective banks when the banks are notconnected for operation. The auxiliary contacts operate in con junction withthe auxiliary contacts of the switc-hesjSO, 104 and 50%, respectively, to prevent the application of potential to the platesof-the tubes before biasing potential has been appliedto their grids and to assure that, when any of the banks 300, 100, or 500 are not in use, their plate circuits are grounded before the rest of the system can be operated. I

r The organization and circuits ofbanks 300 and 500are identical. The construction of bank 300 will be herein describedandis to be understood as applying to both banks.

Cathode heatingcurrent for thetubes 301 is supplied from thegenerator- 13, (Fig. through theconductors 13A, cont acts 362 of switch-"3:60 and transformer. 302. Gridbiasllill ing potential is supplied through the filter 206 (Fla. 2), as hereinbetore desc bed. Networks 303 are connected to the tcs prevent the generation of undesirable oscills. tions in the tube circuits of bank 300.

A. relay 310 is connected in the plate current circuit of each tube. The contacts of these relays are connected in series in one of the con rol circuits, to be hereinafter described, that, it the plate curr nt of any .ube exceeds 1. .'8tltl i1l1lQ l value, the oil be operated to cut oil the the ystei The jacks 311, connected in ries with the relays, provide means whereby the amn'ieter 312 may -2e connected in the plate circuit of each tube to measur the space current supplied to it. aer ol-S connected in hunt to each 1 power supply to 2 ays to provide a path ror the amplirnating current.

ng current for the cathodes of tubes .pplied over the circuit 13c through contacts 462 of switch 460 and the autotransi'orinc-r 414 and the individual transformers 415.

Networks 416 are provided to prevent the establishn'ient of undesirable oscillations in the circuits of the tubes included in bank 400.

Relays 410 are connected in the plate current path between the midpoints of the sec cndary windings of the transformers 415 and ground. The contacts of each relay 410 are connected in circuit with the relay 450 having a contact in the main control circuit. If the plate current supplie to any tube in the bank exceeds a predetermined value the relay 450 will be deenergized to open the main con trol circuit, whereby the oil switch 105 will open to disconnectthe power supply circuit from the system.

Condensers 413 are effectively in shunt to the relays 410 and provide a path for the an'iplilied alternating current. Jacks 411 are provided so that the plate current supplied to each tube may be measured by means of the ammeter 412.

U m't 600 The peak volt-meter circuit 600 is connected to the output lead 602 through the switch 603. This switch is provided with a ground contact (304, by means of which the plate oi the tube 601 may be grounded when the voltmeter circuitis not in use. Switch 603 is also provided with auxiliary contacts 605 which are closed when the switch 603 is in position to connect the plate of 601 to ground.

in l v his I I hrough contacts v82 ot switch 650 and the eistormer 606.

- Control circuits .c three generator are pro sided with cur- 121 which ar ectcd to the relays 22 and i of relays 122 and 123 are lel between the generator three phase leads, will of the relay 125.

coil 119. When the systhe switch 20 (Fig. 2)

u to the right to close the con- Uperatii'ig current is supplied to coil 119 from the direct current *ouggh the series circuit, con oi the relay 125, auxiliary he switch 20 (Fig. 2) auxiliary l circuit breaker 19 1), acts 23 of the circuit breaker 18 liary contacts 24 of the circuit or switch 17, circuit breaker 127, and switch 128. The circuit brekers 19, 1S and 17 are, respectively, provided with the contacts 22, 23 and 24 to cause the oil switch 105 to be opened immediately upon the opening of any of these circuit breakers, whereby the power line is disconnected from the rectitier 100.

The switch 128 may be operated in any of three positions: a right or closing position, a middle or operating position and a left position in which it may be locked open. When the switch is in the middle position, the parallel connected signal lamps 129 permit sutlicient current to flow through holding coil 119 to hold the circuit breaker 105 closed. However, this current is not suliicient to move the circuit breaker from the open to the closed position. When it is desired to bring the circuit into operation, the switch 128 is moved from the locked left hand position to the central position lighting the lamps 129 which are distributed throughout he plant, thus giving an indication that power is about to be applied to the system. A short interval thereafter the switch 128 is moved to the right hand contact thus applying current directly to the holding coil 119 and causing the oil circuit breaker 105 to close. When the switch 128 is released it returns automatically to the central position, in whichposition the lamps 129 ar lighted and sutficient current flows through holding coil 119 to hold the circuit breaker 105 closed.

The-circuit breaker 127 is provided with a in the-main control. circuit.

The maincontrol circuit includes the con: tactsof a'number oi relays associatedwith each pct thennits ofthe system, so that the opening of the contactsoii any. of the relays will'open thev circuitlincluding the coil 130 thereby releasingthe. circuit. breaker 127 and opening the. circuit ofthe holding coil 119,

no-voltage release coil 130 which is connected whereby the oil switch 105 opensto idiscon" through a conductor- ,2511 and the contact blades- 231, 331, 431,.5sr nd 631. hrthe switches 230, 330, 430, .530sand630, to the .bus-hars 24.0, 340, 440, 54a and, 640,. respectively, of/the other unit p The-switches;230,'330, 430, 530 and 630 are provided with contact, blades for connecting the, filament, heating circuits individual to the various units, tothis supply circuit 136;.

In. addition,- these switches provide means whereby the controlcircuits may be 'by-,

passed around an idle unit or units." When closed in their upper positions, the switches 230, etc. serve toconnect the supplyline13a to the filament heating circuit andthe controlcircuit individual to the respectiveop- I 'erative units; fWhenfclosedin theirlower positions, the above inentionedswitches engage contacts to bypass the control circuits individual w idle unit'or units,;but to include the control, circuits associated with succeeding operative .,units, aswill appear later.

.Thewinding of relay130 (Fig. 1 is. connected, by. a, conductor 130a; to. the bus-bar 140, and the contacts offrelays222 and 229 (Fig. 2) 'and 117 (Fig. 1), so thatthe opera-,-. tion of any of the relays 222, 229 or. 117 will cause the relay130 to release. Asignal lamp.

131 is, associated with the lower armature and contacts oi-this relay. A similar relay 132; isconnected through conductors 132a and132b, and; contacts of relay 209'. to. the

b us -barl40.f This relay will'be similarly released by the operation of the relay 209. A

signal lamp 133 is associatedwith the lower arinature of this relay. i 1; The units areprovided withrelaysv 141,

241,341, 441,541 ahdcii, the windings of.

which ar'e connected to'the respective relay buses through the contacts ofthewater fiow control valves 142,242, 342,442, 542 and 642, eaps-study 591210.? the? te rssw hei leased when thewatergflow in any unit. falls below a predetermined value- Signal lamps 143, 243, 343,443,543 and 643 are associated with the lower armaturesof-jthe respective relays. i

2 44, 344,. 444,544 and 644,"respectively. The windings of these. relays are .connec'tedto the respective relay buses through the cage gateswitches. 146, 246, 346,446, 546 and 646 respectively, so that theopening. of any'cagef'gate will cause the. release of the respectiverelay. Signal lamps 145, 245, 345, 445, 545 and 645 are associated'with the lowerfarmatures of the respective relays.

The units 100, 200,300,400 hdhoolare. provided with-relays 147., 247, 347 ,447 and 5 47v respectively; Theserelays are connected. tothe respective relay buses through thermometer controlled .switches149, 249, 449 and549, respectively. 1 The therino ne;

tersfare associated with thecooling water so that. when the temperature of thecooling value, the. corresponding, relay will be operwaterlfor any .unit' exceedsa predetermined atedf Signal lamps l48, 248,1 448 and 548,.are. associated with the lower armatures ofthe respective relays.

1. Each of the units 100, 200, 300,400 and 500 isprovided with relays 150, 250,350, 450 and 550 respectively. Thewindings oiZthese re lays are connected to the respective relay buses throughlthe contacts o;f'relays,107',.224

and 225,310, 410fand 510', respectively, so that therespective relays will beireleased whenever the plate current supplied to any tube of any unit, exceeds a predetermined value; Signal lamps 1 151, 251, 351, 451 and 551 are associated with the lower armatures ofthesefrelafYs. i W I Theunits'200 and'60O relays '252and .652, respectively; The windings of-these relays are connected to the respective relayfbuses. through the auxiliary contacts 215 and 605 of disconnect switches 2121and'603 respectively, Signal lamps 253 and 653 are associated withthe lower arm, tures of the respectiverelaysj r [The units 300,400 and500 are each provided with relays 354 and 356, 4 54 and456,

and, 554 and 556, respectively; [The winding of'relay 354 is connected throu'gh'the auxil iary contact 3091of switch" 307 to thedirect current. supply. The winding of the relay 356 is connected'to the auxiliary contacts 306 oftheiswitc'h 304 (Fig. to the direct,cur-.

rentfsupply The windings of relays- 454,

45 6, 554 and} 556 are associated: with the.

auxiliary, contacts of the corresponding switches, namely,407, 404, 507 and 504, of

the units'400 and 500. Signal lamps355; and

are providedwith tive r'elays, "As noted aboye,these. relays are 7 9421 15 lb? 41 iiidl'fie ii this was t i 1 Each unitis also provided with relays 144,

tively, provide means for connecting the different phases of the cathode heating current circuit 13a to the cathodes or" the tubes included inthe respectiveunits.

O partition Let us assume, for example, that it is ,desired to operate the amplifiersystenito in these positions, the relays 554 and 556 will.

both be operated thus providing a closed cir- 01110 tnrough their upperarinatures between the switch arms 559 and558 for the main circuit will be opened and it will be impossible to hold the oil switch 105 closed.

and rectifier tubes is turned on, causing the plungers of the control devices 142, 242,- 342, 442, 542and 642 to be raised, closing their contacts. The relay circuitsare energized by starting the generator 25. Under this condition, all of the relays necessary to normal operation will be actuated to close the contacts in the control circuits. Heating current is supplied to the cathodes of the tubes by closing the circuit breakers 17 and 18. The grid biasing potential-circuit is energized by closing the circuit breaker 19. The circuit breaker 127 is then closed and after the switch 20 is moved to its right hand position and switch 212 to its left hand position, the oil switch 105 is operated by the, operation of the switch 128 as described above." The rec tifier unit will then be operative with all of the signal lights 131, 133, 143, 148, 145. and 151 lighted. I r

I The occurrence of any undesirable operating condition in the rectifier circuit 100 of the trouble is indicated. For example, it

any f th horn gaps 115, 227-or 220 arcs over thecorresponding relay 117, 229 or 222 will be operated to open the circuit through the coil of the relay 130, thereby causing it to f release and thereby open the main control circuit. Similarly, if the grid spark gap 207 arcs over the relay 209 will be operated to open the circuit through the coil of the relay 132.

These operations which put the unit100 The water flo'wto cool the plates of the amplifierinto operation also bring the unit 200. into operation. I This unit will now operate with the signal lamps 243, 248, 245', 251 and 253 lighted. It the water flow fallsbelow the re quired minimum the plunger of the control device 242 will drop, opening the plunger contacts-and releasing relay 241 and opening the control circuits to disconnect the plates and filaments from their supply sources and p to extinguish the light 243, whereby the source of the trouble is indicated. Similar action takes place if the temperatureof the cooling'water exceeds the maximum, if the.

cege'gate is opened, or it the plate current exceeds the desired maximum.

T o'bring the unit 300 into operation it is necessary to first-close the switch 304fr0m the grounded to the right hand or closed position and then to move the switch 307 from-the grounded to the left handor closed position. These operations first supply grid biasing potential to the tubes of bank-300 and then plate potential. It the order of operationis reversed th'eniain control circuit will beiopjenedcausing the release of the oil switch 105. This fact can be evident from an examination of the circuitsof relays: 354 and 356. ltboth. the switches 304 and 307 are, in their grounded positions,both the relays 354 and 356 will be operated and themain control circuit will be closed through the middle arma: ture'oi the relay 354. then the switch 304 is movedto its closed position the relay 356 willbe released to completethe main control circuit through the middle armature of that relayin parallel with the middle contact of relay=35 4. VVhe'n the circuit through the middle armature of the relay 354 is opened,

dueto the release :ofthat relay by the closing of the switch 307, the main control circuit will remain'closed. However,.,itthe switch 307 isfclosed in its operative position before the "switch 304, the main controlcircuit will be opened at. the middle contact of 35 4, be-

cause this relay-is deenergized, and the oil;

switch will be released.

' i l similar set ofoperations are requiredto bring'the uniti400 into operation.

All that isrequiredto bring the voltmeter circuit '600 into an operating condition is. to 11101 813116: switch 603 from its grounded positionto :the left hand or closed position. I

When tllfifllIiitS 300, 400 and600 are operating, their corresponding signal, lamps will be lighted and it any un desired" operating condition occurs, the corresponding relay will beoperated to disconnect the power and e tinguish the respective light to indicate the trouble.

. If for any reason it is desired tosubstitute the/bank 500 for either ofthebanksSOO or' 400,;it is necessary toshut down the. sys:

tem is brought into operation i y a series of operations similar to that d( crihed above.

What is c aimed is:

l. A higl'i power transmitter (o-man amplifier system having a plurality of stages, a rectifier system for applying space current to said amplifier system, said systems including water cool d space discharge devices, means for maintaining a circulation of cooling water, a source of cathode heating current for said devices, an alternating current source for supplying space current to the rectifying devices, a master control cir cuit including means controlled by said cool ing water for controlling the connection of said alternating current source to said rectitier, and an auxiliary control circuit includ ing means controlled by said cooling water for controlling the connection of said source of cathode heating current to said devices.

2. A high power transmitter comprising an amplifier system having a plurality of stages, each including water cooled space discharge devices,'a source of cathode heating current and a source of space current for aid devices, a control system including means individual to each stage'and responsive to different undesired operating conditions therein for controlling the connection of said sources to said devices, means for connecting certain of said stages together for joint operation and for rendering at least one other stage inoperative, and switching means in the control system for including therein the means controlling the connection of said sources to'the operative stages and for by-passing the connection controlling means of the inoperative stages.

3. A high power transmitter comprising an amplifier system including a plurality of stages, each having water cooled electric dis charge devices, a source of cathode heating current and a source of space current for said devices, a control system comprising a plurality of means individual to each stage and responsive to different undesired operating conditions in that stage, and means controlled by said responsive means for controlling the connection of said sources to the discharge devices, and a circuit including a signal device associated with each of said responsive means.

4. A high power transmitter comprising an amplifier system including a plurality of stages, each stage including water cooled electric discharge devices, each having a cathode, an anode and a control electrode, a source for supplying heating current to said cathodes, a source for supplying biasing potential to said control electrodes, a source for supplying space'current to said devices, switching means for connecting said sources to said devices, control circuits associated with said system including a plurality of means individual to each stage for controlling the operation of the cathode heating current and space current switching means, a plurality of means each responsive to different undesired operating conditions in each stage for actuating the controlling means, and other switching means for preventing the actuation of the control electrode and space current switching means except in a predetermined order.

In witness whereof, I hereunto subscribe my name this 23rd day of January, 1928.

MILES E. FULTZ. 

